Electron discharge system



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by His Attorney.

v25 ticularity in the appended claims.

Patented Nov. 13, 1934 UNITED STATES rrr o-Frice ELEoTRoN DISCHARGE SYSTEM n New York applicati@ May 17,1999, serial No. 458,892

6 Claims.

My invention relates to electron discharge systems and more particularly to certain improvements in systems employing electron discharge devices of the magnetic field divided or split anode type.

Electron discharge systems of the type to which my invention relates are shown and described in copending applications, Serial No. 397,893, filed October '7, 1929, by Norvel Douglas; Serial No.

16 320,709, iiled November 20, 1928, Serial No.

389,067, led August 28, 1929, by Elmer D. Mc- Arthur, and in my copending application Serial No. 398,249, iiled October 8, 1929, and entitled Electron discharge apparatus. -My present application is a continuation in part of my above mentioned copending application.

My present invention has for its purpose to provide means whereby certain of the operating characteristics of systems of the type indicated may 20 be improved and whereby, in general, the eiciency and practicability of these systems is. increased.

'Ihe novel features lwhich I believe to be characteristic of my invention are set forth with par- My invention itself, however, both asto its arrangement and method of operation together with further cbjects and advantages thereof may best be understood by reference to the following description taken in connection with the accompanying drawing in which Fig. 1 represents an embodiment of my invention, and in which Figs. 2, 3

and 4 represent certain of the operating characteristics thereof.

Referring to the drawing, I have shown in Fig.

l an electron discharge device of the split, or

divided anode type. Connected between the anodes of the discharge device is an oscillatory circuit 2 in which oscillations are produced by action 4,0' of the discharge device. This circuit is coupled to a suitable load circuit 3 Which, in the drawing, is represented as an antenna.

A cathode 4 extends longitudinally ofthe discharge device and between the two anodes. This cathode is heated to incandescence by means of a source of electromotive force 5. A suitable electromotive force is impressed between the cathode 4 of the discharge device and the anodes thereof by means of a source 6 which is connected between the cathode and the midpoint on the inductance of the oscillatory circuit 2. I have represented at '7 a suitable coil extending about the discharge device and which is energized from a source of uni-directional potential 53 8. Thus the coil produces a uni-directional magnetic field extending longitudinally of the discharge device and between the anodes thereof. As .thus arranged the system comprises a now well known oscillation generator particularly adapted for the production of oscillations of short wave length.

I have found that the efciency and certain of the operating characteristics of apparatus of the type described may be very markedly improved by including in the circuit of the source of potential 6 a resistance which I have indicated at 9 in the drawing. Thisresistance may vary in value dependently upon the type of discharge device used, but I have found, in general, that the value of thisresistanceshould be relatively high, and suchA that the anode potential is given a poor regulation characteristic. That is, by reason of this resistance, the voltage applied to the anodes before current starts to now and before oscillations start, is higher than the voltage applied to the anodes during the flow of space current. For example in a particular case of a discharge device in which the cathode anode voltage was 1500 voltsand whichhada power rating of 25 watts the proper value of theresistance was in the neighborhood ofv 5000 ohms. Through empirical methods I have found that the value of this resista-nce is approximately equal to the eld intensity ingausses divided by the anode current expressed in amperes.

In Fig. 2 I have shown comparative characteristics of systems of the type indicated With and without the resistance 9 and from which certain of the advantages of my invention are apparent. Thus for example, in this iigure the curve A represents the relation between the anode current and the intensity of the magnetic field between the anodes of the discharge device with the resistance 9 omitted from the circuit. It will be seen that as the field strength is increased from Zero, the plate current is at first diminished slightly and then rises somewhat abruptly to a relatively high value after vwhich upon further increase of the field strength the plate current diminishes in accordance with the right-hand portion of the curve A until a point is reached at which the plate current suddenly drops to zero.

The curve B represents the same characteristic of the system in which a resistance of 5000 ohms is included in the anode circuit of the discharge device. It will be seenthat in this 'system as the field strength is increased the plate current gradually diminishes in a definite predeterminable relation until a certain iield intensity is reached at which the plate current drops suddenly to zero. '1110 Thus it will be seen that by use of the resistance in accordance with my invention, the abrupt peak in the anode current eld intensity curve is eliminated, and thus excessive heating of the discharge device due to variations in the field strength is avoided.

The curve C of Fig. 2 represents the relation between the oscillatory current of the circuit 2 of the same discharge device when no resistance is employed in the anode circuit. It will be seen that as the eld strength is increased, oscillations start at about the point at which the anode current is maximum and increase rapidly and at a diminishing rate until a certain field vintensity is reached corresponding to the point 10 atgwhich.

oscillations suddenly cease. If now the field strength be diminished, it will be found that oscillations will not again start until a point is reached indicated at 11 at which oscillations start with full intensity; that is, with intensity indicated lby the curve C at thereld strength corresponding to the point 11. Thisindicates that for stable operation of the discharge device it is necessary to use a value of eld intensity corresponding to the point 11. This point is indicated by the point 12 upon the curve C. To obtain maximum efciency computed as the relation between the output high frequency energy and the input energy of the discharge device, it is desirable to operate the discharge device at approximately the maximum point ofthe curve C as indicated for example atthe point 13. Thus there is a comparatively wide range of rleld intensity between the point of maximum eiciency and the point where stable operation is procurable which can not be practically employed because of the unstable operation of thedevice. .l

The curve D represents the same characteristic ofthe discharge device employing 5000 ohms in the anode cathode circuit. It will be seen that in general the curve is shifted somewhat to the left of the curve C. The point 13' represents that at which maximum efficiency of the discharge device may be had, and the point 12 that at which stable operation may be had. The range of eld intensity variation over which unstable operation is had is thus materially decreased. Thus it is possible to use a field strength which more closely approximates that at which maximum e'iciency of the device is obtained and at the same time secure stable operation of the device. Thus the eiciency of the system is increased.A

Referring to Fig. 3,1 have shown further characteristics of discharge systems of the type indicated. In this gure curve E represents the relation between the anode current and anode voltage of an oscillation generator of the type indicated, overa certain'range, whereas the curve F indicates the relation between the oscillatory current inthe oscillating circuit and the anode voltage.

Referring to the curves of this gure, it will be seen that if the anode current is adjusted at a `value corresponding to 14 on the curve E, the oscillatory current in the oscillating circuit will correspond to the point 14' on the curve F. If now the anode voltage be increased to a point 15 on the curve E, it will be seen that the plate current will be increased by an amount indicated as AIb on the gure, whereas the change in high frequency, current in the oscillating circuit is indicated as AIa on the drawing. Thus it will be seen that the anode current in the device is increased and hence there are greater losses in vsate for the voltage increase.

' and cathode maybe maintained at a more nearly constant value and the current in the oscillating circuit will thus be less affected by the change. In this way I have found that avery material increase in the eliciency of the device may be obtained by including this fairly large resistance in the anode circuit. These considerations point to a value of resistance which may be determined from the slope ofI the anode current anode voltage characteristicand which may be expressed as a constant multiplied by the slope of this characteristic.

In Fig. 4 I have shown an additional characteristic of my system indicating the yrelation between the efficiency of the system taking into consideration the energy dissipation in resistance 9 and the value of the resistance. It will be seen that as the resistance increases thegeiciency is at rst diminished and then rapidly increases to a maximum value after which it again diminf ishes. Of course the proper value of resistance is that at about which maximum efficiency is obtained.

While in this vdescription I4 have mentioned particular values of the resistance 9 ,3 it willof course be understood that I donot wish to vbe limited thereto `since as is readily apparentA from Fig. 4 of the drawing the valueof this resistance may vary-over a fairly large range and-still produce the advantages resulting from my invention.

What I claim as new and desire to secure by vLetters Patent of the United States, is:

1. An 'oscillation generator comprisingv a discharge device having oppositely disposed anodes, a cathode arranged between said anodes, an oscillatory circuit Vvconnected between said` anodes, a source of direct current potential connected ,between said anodes and cathode, means for producing a unidirectional magnetic eld between said anodes having such value that oscillations are produced in said oscillatory circuit and means for eliminating rapid variations in current ilowing between saidl cathode and anodes with respect to variations in eld strength over a certain range thereof.

2. An oscillation generator comprising a discharge device having oppositely disposed anodes, a cathode arranged between said anodes, an oscillatory circuit connected between said vanodes, a source of direct current potential connected beltween said anodes and cathode, means for producing a unidirectional magnetic eld between said anodes having such value that oscillations are produced in said oscillatory circuit and means for eliminating rapid variations in current flow'- ing between said cathode and anodes with respect to variations in field strength over a certain range thereof, said means comprising a resistance con'- nected in circuit with said source of potential.

3. An electron discharge system comprising a discharge device having oppositely disposed anodes, a cathode arranged between said anodes, an oscillatory circuit connected'` between .said

anodes, a source of potential connected between said cathode and said anodes, means for producing a unidirectional magnetic eld between said anodes and a resistance connected in circuit with said source of potential, said resistance hav ing a value determined by the slope of the curve expressing the relation between the current owing between the cathode and anodes and the potential appearing between the cathode and anodes.

4. An oscillation generator, comprising an electron discharge device having oppositely disposed anodes, a cathode located between said anodes, a source of potential connected between said cathode and said anodes, an oscillatory circuit connected between said anodes, means for producing a magnetic eld between said anodes whereby oscillations are produced in said oscillatory circuit, said oscillations being unstable over a certain range of variation in intensity of said magnetic iield and means including a resistance in circuit with said source of potential for reducing the range of variations of said iield strength over which unstable operation occurs.

5. An oscillation generator, comprising an electron discharge device having oppositely disposed anodes, a cathode arranged between said anodes, an oscillatory circuit comprising an inductance connected between said anodes, a source of potential connected between said cathode and said anodes, means for producing a magnetic eld between said anodes of sufficient intensity to cause oscillations to be produced in said oscillatory circuit, and means whereby the potential applied to said anodes has poor regulation, said means comprising a high resistance connected in circuit with said source of potential.

6. An electron discharge device oscillator comprising an hermetically sealed container wherein are contained an electron emitting cathode, a plurality of anodes disposed thereabout, and means for subjecting the electrons flowing from said cathode to said anodes to a magnetic eld,

and, a source of potential having poor regulation y connected to said anodes whereby the voltage applied to said anodes is higher prior to the time when oscillations start.

KENNETH C. DE WALT. 

